The BT210S series are auto-focusing laser cutting heads released by RAYTOOLS AG in 2017 for fiber laser processing with 1.5KW or less. This products have a built-in motor drive unit, which drives the focusing lens through a linear mechanism to change position automatically within 17mm. Customers can set the program to achieve continuous focus that completing the rapid piercing and cutting material with different thickness. BM109 use the D28 diameters lense set to collimate and focus the laser beam, which can achieve the diffraction-limited optical effect. The design of water-cooled structure allows laser heads to work stably and chronically.